(a) Field of the Invention:
The present invention relates to a projector-type head lamp for use on vehicles, and more particularly to a projector-type head lamp in which there will not appear on the light-dark limit any color fringes caused by the chromatic aberration of the objective (convergent lens).
(b) Description of the Prior Art:
Heretofore, approaches have been proposed to reduction of the color fringe developed near the light-dark limit as caused by the chromatic aberration of the convergent lens. One of them is disclosed in, for example, the U.S. Pat. No. 4,562,519 in which localized deflector elements are disposed on the back surface of the convergent lens or in the proximity thereof to deflect the light having passed through the upper and lower portions of the convergent lens, thereby reducing the color fringe developed near the light-dark limit. Such localized deflector elements are formed integrally with the convergent lens as parts mounted on the upper and lower portions of the back surface of the convergent lens and permit to reduce partially the intense coloring resulted from the vertical dispersion of the light having passed through the upper and lower portions of the convergent lens, but do not permit to reduce the coloring due to the dispersion of the light passing through the portions including those around the center of the convergent lens. Therefore, there still develops near the light-dark limit in the arrangement disclosed in the U.S. Pat. No. 4,562,519 a color fringe caused by the dispersion of the light having passed through other portions than the upper and lower portions of the convergent lens.